Daniel Richards from Lapworth will be running over 200 miles in four days in memory of his father-in-law John Artlett-Coe who passed away from cancer.
The 30-year-old will begin the marathon challenge in Llandudno, Wales on August 18.
Daniel will run 50 miles a day as he crosses over the hills of Blaenau Ffestiniog, heading south to Snowdonia National Park, passing through Rhayader before crossing the Brecon Beacons National Park, and finally, running south into Barry.
“I will have one support rider following on a quad bike with water, food supplies, first aid and weather protection, just in case the weather worsens. But other than that it will be head down and keep on running,” said Daniel, an electrical engineer.
“I’m a little nervous but quietly confident.
“It’s been about a year in the planning but three months ago I just thought ‘I’m going for it.’ I’m 30 now, I wanted to do it before my knees go.
“I’ve been running for about 10 years but in preparation for this, I’m doing a punishing training program of core and cardio vascular work and diet has played a massive part.”
All the money raised will go towards Macmillan Cancer Support and Daniel is also holding coffee mornings and raffles ahead of the run to help reach his £2,000 target.
“They are doing a fantastic job,” he added “It’s definitely a worthy cause to do this for.”
To make a donation or to sponsor Daniel, visit www.justgiving.com/Daniel-Richards3.